The in-system concentration of water treatment agents in industrial water systems is conventionally controlled based on intermittent measurements of the concentration of the target specie(s) and/or the concentration of the water treatment agent(s) in the water of the system or unselective measurements (e.g., conductivity). The control goal of most water-treatment programs is to maintain a predetermined or optimum ratio of water treatment agent(s) to target specie(s) (for instance scaling ions, contaminants and the like) in the water of the system. The in-system concentration of the water treatment agent(s) is regulated to attain or maintain this ratio or the target specie concentration is adjusted to meet specified values. For instance, if the concentration of hardness ions entering a boiler system increases, an increase in the in-system concentration of the water treatment agent(s) may be needed to maintain the water treatment agent(s) to target specie(s) ratio goal. The measurements of the concentration of the target specie(s) and/or the concentration of the water treatment agent(s) in the water of the system, and the responsive in-system concentration adjustments, are commonly based only on occasional grab samples, taken for instance once or twice per shift (a shift commonly encompassing about 8 to 12 hours of system operating time) or once every several days. Concentration determinations for water treatment agents and/or target species in industrial water systems have heretofore generally been based on classical (wet chemistry) analysis techniques, conductivity and/or hydraulic meter readings, for instance water flowmeter readings.
Classical analysis techniques for determining the concentration of a target specie and water treatment agents in a water system are usually somewhat cumbrous and/or protracted, and/or provide results that are merely estimates and/or variable (for instance, dependent upon a person's laboratory technique). Long time delays typically exist between changes in system operation and a compensating change in treatment dosage. For example, phosphate concentrations are determined by a spectrophotometric (colorimetric) test. Concentrations of pyrophosphate and organic phosphorus compounds are determined using the same spectrophotometric test with a digestion (reversion) step. Titration methods are routinely employed to determine the concentration of hardness ions, such as calcium and magnesium, and the concentrations of carbonate and bicarbonate, in the water of the water system. Such analysis methods are susceptible to interferences (e.g., turbidity) and/or are subjective (visual observation of color change). These values, and often the ratio therebetween, are then used to manually set the in-system target concentration of the treatment chemicals, such as scale inhibitors and neutralizing amines.
The more accurate a conventional manual (grab sample) analysis technique, the more protracted that technique or its response time can be. Feedback information can at times even be days behind the sampling and hence of little value in providing data from which a dosage-regulation response can be determined. The water system consumption of a water treatment agent may well have changed during the elapsed interval between the taking of the sample and the analysis results.
Even when accurate indications of the mass or volume of a water treatment agent feed delivered to a system are available, and accurate water treatment agent residual concentrations are available, if the residual concentration determinations are based on grab or intermittent samples, any extrapolation therefrom to a value for the system demand and/or system consumption for the water treatment agent is based on fragmentary data and outdated information. A change in the system consumption may not be detected until it has had a significant impact on treatment agent consumption and system performance. When the detection of system consumption change is delayed, the responsive regulation of a treatment agent's in-system concentration or response to system operation will invariably be late and system performance may suffer. When the responsive regulation of in-system concentration is late, underfeeding or overfeeding of the treatment agent routinely will occur to some extent between the time the system consumption of the water treatment agent has changed and the time the treatment agent in-system concentration and/or system operating parameter (e.g., alkalinity adjustment) is adjusted.
In an industrial water system plant the use of any estimated, variable, intermittent, fragmentary or historic data severely diminishes the sensitivity of any demand-responsive regulation of the water treatment agent in-system concentration and/or diminishes the ability to follow changes in the treatment-agent system demand or system consumption with appropriate compensations to the water treatment agent in-system concentration.
Conventional procedures for regulating water treatment agent in-system concentration are further complicated by other imprecise evaluations of operating parameters. The rates at which the water treatment agent is being fed to and/or removed from the industrial water system and/or other operating parameters having an influence on the in-system concentration of the water treatment, may defy precise measurement unless inert tracers and selective analytical methods are used. The readings and/or settings on feed and blowdown equipment and/or lines are seldom unquestionably reliable and often complicated by multiple sources of blowdown and makeup and changes in composition of these water samples. Fluctuations in the concentrations in the target species and the water treatment agent may stem from a variety of system conditions, such as dilution when other materials are charged to the system, concentration by evaporation or other means, unaccounted loss of fluid from the system and the like, some of which parameters may not be accurately known. Generally all sources of water intake and loss, and all sources of water treatment agent intake and loss, cannot be known precisely and continuously unless inert tracers and selective analytical methods are used.
A sensitive, selective and rapid demand-responsive control of water treatment agent in-system concentration would render most any industrial water system more efficient. Overfeeding of a water treatment agent is unnecessarily expensive, may at times diminish the recycling potential of waste water discharged from the system and may also at times impair system operation. Underfeeding of a water treatment agent almost inevitably impairs system operation, the imbalance between an underfed water treatment agent and the target species leading to higher levels of deleterious effect(s) from which relief is sought by the water treatment. In some water systems an imbalance between the in-system concentrations of water treatment agents and the system's water conditions and/or target species can severely diminish the efficiency of the system. For instance the efficiency of a system's temperature conditioning performance, such as heat exchange and steam generation, may be reduced which in turn may diminish the performance of a process to which it is adjuvant.
A sensitive, selective and rapid demand-responsive regulation of water treatment agent in-system concentration that permits the in-system concentration of water treatment agent(s) to be adjusted in response to real-time system conditions is not provided by the conventional methods.
It is an object of the present invention to provide a method or process for monitoring the concentration of a target specie(s) in a water system, thereby permitting a responsive regulation of the in-system concentration of one or more water treatment agents and/or adjustment of system operating parameters (e.g., alkalinity, etc.) It is an object of the present invention to provide such a method or process that can be conducted on-site in a very short time period. It is an object of the present invention to provide such a method or process further including the regulation of the in-system concentration of at least one water treatment agent and/or system operating parameter in an industrial water system in response thereto. It is an object of the present invention to provide such a method or process that can be conducted on-site in a very short time period, preferably on a continuous basis. It is an object of the present invention to provide in an industrial water system one or more monitorings of target specie(s) on-site in a very short time period, preferably on a continuous basis. These and other objects of the present invention are discussed in detail below.